February 27, 2014

Exxon Valdez Oil Found Two Decades Later Hiding Among Boulders

According to a report presented at the American Geophysical Union meeting on Wednesday, researchers from the US Geological Survey have found intact oil left over from the Exxon Valdez spill off the coast of Alaska 25 years ago.

The researchers noted that the amount of remnant oil they found is just a tiny fraction of the spill that poured out of the infamous oil tanker in March 1989.

Gail Irvine of the USGS’s Alaska Science Center said certain configurations of boulders along the Alaskan shoreline have been found to harbor small pockets of oil.

“To have oil there after 23 years is remarkable,” Irvine said. “We have these marked boulders whose movement we’ve been studying for more than 18 years. The oil itself has hardly weathered and is similar to 11-day-old oil.”

Chemists at the National Oceanic and Atmospheric Administration and Woods Hole Oceanographic Institution were able to positively link samples collected in the Shelikof Strait, southwest of the spill, and other areas to the ecological disaster.

“Very old oil spills can be found to still have oil,” said Christopher Reddy, an oil spill specialist at WHOI. “We were capable of fingerprinting that oil.”

Reddy emphasized that there were some positive aspects to finding remnants of an oil spill 25 years later.

“One lesson is that if you are responsible for cleaning up a spill, you want to be proactive about cleanup behind the boulders,” said Reddy.

He added that future spill responders should try to keep oil from sitting in areas where it can last for years or decades.

“We are taking advantage of these samples as a natural laboratory,” Reddy said.

Another study from NOAA and Stanford University published earlier this month found that oil from spills can disrupt fish heart cells, resulting in a slowed heart rate, reduced performance and irregular heartbeats – potentially leading to cardiac arrest and even death.

Oil interferes with cardiac cell excitability, contraction and relaxation, the researchers found. All of these processes are vital for normal functioning of the heart. The researchers found that very low concentrations of crude oil disrupts the specialized ion channel pores—where molecules flow in and out of the heart cells—that control heart rate and contraction in the cardiac muscle cell.

In cells throughout the heart, this signaling pathway is what pumps blood out of the heart on every beat. In the hearts of most animals, humans included, the protein components of the signaling pathway are highly conserved.

According to the findings, oil blocks the potassium channels distributed in heart cell membranes, which increases the time to restart the heart on every beat, prolonging the normal cardiac action potential and slowing the heartbeat. Because this channel is found throughout vertebrates, it raises the possibility that animals as diverse as tuna, turtles and dolphins might be affected in similar ways by exposure to crude oil.

“These new findings more clearly define petroleum-derived chemical threats to fish and other species in coastal and ocean habitats, with implications that extend beyond oil spills to other sources of pollution such as land-based urban stormwater runoff,” said study author Nat Scholz, leader of NOAA’s Ecotoxicology Program.